Electron device and method of manufacture



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G. J. DRIES ET AL ELECTRON DEVICE AND METHOD OF MANUFACTURE Filed May 26, 1964 2 Sheets-Sheet l Mlfh v vv

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WITNESSES PRIOR ART Fig.5.

Fig.6.

INVENTORS Gerald J. Dries and Richard L. Giovononi.

CM F

ATTORNEY Aprfi M, 1%? G J DRlEs ET AL 3,313,324

ELECTRON DEVICE AND METHOD OF MANUFACTURE Filed May 26, 1964 2 Sheets-Sheet 2 Fig.3.

United States Patent @fitice 3,3l3,324 Patented Apr. 11, 1957 3,313,324 ELECTRGN DEVICE AND METHOD OF MANUFACTURE Gerald J. Dries, Arlrport, and Richard L. Giovanoni,

Bath, N.Y., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed May 26, 1964, Ser. No. 370,163 8 Claims. (Cl. 14971.5)

This invention relates to electron discharge devices and more specifically to improvements in the electrode structures thereof. In particular, this invention deals with an electron device having concentric or coaxial grid electrodes with the active portions of the grid wires of each of the concentric grids aligned with each other, and with a method of assembling and manufacturing said concentric grid electrodes into electron devices.

A grid structure of the type to which the present invention relates usually comprises a pair of relatively heavy wires which are generally known as support wires or side rods about which is wound a relatively thin grid wire. That portion of the grid wire across which the beam of electrons flows is designated as the active portion, whereas that portion secured to the side rod may be known as the connecting portion. In many types of electron devices, such as a 6DQ6, or a 17JZ8, a plurality of grid electrodes are mounted coaxially with respect to each other about a cathode element. One of the major problems encountered in these electron devices is that of maintaining the active portions of the grid wires of successive grid electrodes in an aligned relationship. It may be seen that if the active portions are not aligned that the stream of electrons flowing from the cathode to the anode may be substantially impeded by a misplaced grid wire. As a result, the electrons which are being accelerated to ward the anode will strike one of the concentric grid electrodes thereby decreasing the efiiciency of this device. It has been calculated that in an aligned two grid electrode device that only one out of every 20 electrons flowing from the plate to the anode will be absorbed by the second grid electrode whereas if the coaxial grid electrodes are not ali ned that as many as one out of everv three electrons may strike the second grid electrode thereby being absorbed and wasted. As a further harmful result, the current absorbed by the misaligned rid electrode will be radiated in the form of heat which may materially shorten the life of the electron tube well as its associated circuit components.

One suggestion for solving this problem has been set forth wherein the grid wire is wound about a specially tooled mandrel. When the winding has been completed the mandrel is expanded thereby imparting a deformed configuration to the grid wire so that the active portions of the concentric grid electrodes will coincide with each other. It may be seen that this method of aligning the grid electrodes would necessarily involve a spetiial inandrel having therein a plurality of precisely machined grooves. Further, this method could not be easily adapted to the mass production of grid electrodes with extremely fine grid wires.

A common method of forming grid electrodes is to wind the grid wire in helical fashion upon the well known grid lathe. In the past with such a machine, it has not been possible to completely align the active portions of the coaxial grids with each other. If the turns of the different coaxial grids had the same pitch then clearly they will not have the same helical angle. Conversely, if they are arranged to have the same helical angle they will not have the same pitch. As a compromise solution, it has been the practice to arrange the grids so that the central device as point of the active portions of the grid electrodes will be aligned with each other. In theory, such an alignment would appear to provide an adequate solution for this problem. However, in the normal assembling processes the coaxial grids are aligned by hand by first ad usting one side rod and then the other to achieve the alignment. After one side has been aligned by such a process, it is necessary to align the grid wires of the other side of the grid electrode. As experience in this field has shown, it is necessary to align both sides of the grid electrodes to insure alignment with the other grid electrode. Such alignment has proven only partially satisfactory. In the first place, such alignment is a comparat vely long and tedious process involving a costly expenditure or labor. Secondly, such alignment involves the deformation of the side rods which when later processed will often return to the predetormed position thereby misaligning the concentric grid electrodes.

Accordingly, it is the general object of this invention to provide a new and improved electron tube device.

it is another object to provide an improved electron discharge device wherein the active portions of adjacent electrodes are aligned with respect to each other.

i It is a further object of this invention to provide a new and improved method of winding helical coils wherein the pitch oi the coil may be varied as the coil is being wound.

It is a still further object of this invention to provide a method of winding and assembling coaxial grid electrodes in which the prealignment placed in the active portions of the grid wires may be accomplished as the grid electrode is wound upon a lathe.

It is a still further object of this invention to eliminate the second alignment operation during aligning of the grid electrodes.

Briefly, the present invention accomplishes the abovecited objects by providing an improved electron discharge device wherein the active portions of the turns of adjacent electrodes are aligned with respect to each other. In a typical electron discharge device, two or more grid electrodes may be placed coaxial of each other having the turns of the electrodes wound helically with connecting portions of the electrodes secured to side rods. Specifically, the alignment of the active portions of the electrode is accomplished by securing the connecting portions of the electrodes to their respective side rods at different pitches so that the active portions of each electrode is formed at the same pitch. In one specific embodiment, the electrodes may be fixed upon the side rods by placing their connecting portions within notches which have been cut into the side rods at varying predetermined pitches with respect to the side rods. The notches may be machined into the side rods as the grid wire is being wound upon a lathe. The resultant product from the grid lathe is a plurality of grid electrodes all of whose active portions are aligned at the same pitch with respect to their side rods. In addition, the invention discloses an improved method of winding the helical grid electrodes wherein the pitch or angle of the grid wire is varied as the electrode is being wound. Specifically, notches are placed into the side rods at predetermined angles whereby as the grid wire is placed into the notches, the pitch of grid wire may be repeatedly varied. Further, by prealigning the pitch or angle of the active portions of the grid electrode, the process of aligning the concentric grids may be materially simplified in that the adjustment of the side rods may be accomplished from a Single perspective of the grid electrode assembly.

Further objects and advantages of the invention will become apparent as the following description proceeds and features of novelty which characterize the invention will be pointed out in particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the invention, reference may be had to the accompanying drawings, in which:

FIGURE 1 shows a partial front view of a grid lathe upon which the grid electrodes are wound;

FIG. 2 shows an isometric view of an assembly comprising the adjustable clamp and the yoke for mounting the notching wheel, which assembly is a part of the grid lathe shown in FIGURE 1;

FIG. 3 shows a sectional view of the yoke shown in FIG. 2;

FIG. 4 shows a view of an electron tube device containing an embodiment of this invention;

FIG. 5 shows an enlarged view of a grid electrode assembly representing an arrangement typical of the prior art;

FIG. 6 shows an enlarged view of a grid electrode assembly representing one embodiment of this invention;

FIGS. 7 and 8 show respectively a partial view of the outer and inner grid rods shown in FIG. 6; and

FIG. 9 shows a plan view of the grid assembly shown in FIG. 6.

Referring now to FIGURE 1, there is shown a grid lathe upon which the grid electrodes of this invention may be wound. With specific reference to the particular grid machine shown in the drawing, the grid lathe comprises a bed plate 11), upon which is supported at one end a head stock 12 and at the other end a tail stock (not shown). A tubular draw bar 14 is provided at one end with a strip clamp 16 to which is secured two side rod wires 18. Spools 28 contain a supply of the side rod wires 18 and feed the same into a head spindle 26. The side rod wires 18 are then passed through channels in the head stock 12 into a mandrel 20 where it is successively operated on by a notching wheel 22 and a peening wheel 24. The notching wheel 22 is operatively positioned by a yoke 32 which is secured to the head stock 12 by an adjustable clamp 30. A spool not shown is provided to supply a grid wire or filament 34 which is drawn upward onto the side rod wires 18.

The winding operation is started by securing the pair of side rod wires 18 to the strip clamp 16. The tubular draw bar 14 is connected to a screw means (not shown) which is capable of simultaneously pulling the tubular draw bar 14 in a direction toward the left (as shown in FIGURE 1) and imparting to it a rotational motion. The notching wheel 22 is so positioned that its periphery cuts a notch or groove in each side rod wire 18 as the side rod wire 13 is carried under the notching wheel 22. The mandrel 26 is placed between the two side rod wires 18 and forms a base against which the notching wheel 22 and the peenin g wheel 24 acts. It is noted that the shape of grid electrode is partially determined by the shape of the mandrel 20. The grid wire 34 is initially secured to one of the side rod wires 13 in a manner well known in the art. As the strip clamp 16 is drawn with a linear and also rotational motion, the grid wire 34 is wound about the side rod wires 18 and mandrel it) in a helical fashion. The grid wire 34 is fed onto the side rod wire 18 so as to fit into each notch as it is cut by the notching wheel 22; further, as the side rod wires 18 are rotated, the peening wheel 24 will deform or peen a portion of the side rod wire 18 so as to secure the grid wire 34 therein. This process will continue until strip clamp 16 has run its length, and then the process will be repeated. The product of this operation is a long section of side rod wires 18 with the grid wire 34 wound helically thereabout; this section of side rod wire 18 is then cut to the desired length in order to form a plurality of grid electrodes. The individual grid electrodes may be then placed on a sizing mandrel (not shown) where the grid wires may be stretched to impart the final shape to the electrode.

In FIGURES 2 and 3, there is shown an adjustable assembly for mounting the notching wheel 22 to the head stock 12. In FIGURE 2, there is shown the adjustable clamp 30 with an aperture 84 therein for receiving a connecting rod 86 of the yoke 32. The rod 86 is adjustably secured within the aperture 84 by a clamping bolt 89 which extends through holes in extending portions 82. The precise angle at which the notching wheel 22 cuts the side rod wires 18 may be determined by adjusting the position of the yoke 32 with respect to the clamp 30 by a Vernier protractor.

Referring now more specifically to FIGURE 3, there is shown the yoke 32 upon which is mounted the notching wheel 22 by an arbor 88. The arbor 88 extends through holes in either leg of the yoke 32 and is variably secured within the yoke 32 by an adjustable bearing 94. The adjustable bearing 94 is threaded on its periphery so as to be received within a threaded opening of the yoke 32. A pin 98 is received within an aperture 96 of the arbor 88 and is attached to the adjustable bearing 94 so that when the arbor 88 is rotated by an instrument such as a screwdriver, the arbor 88 may be repositioned within the yoke 32. Therefore, the lateral position of the notching wheel 22 may be adjusted precisely in either direction. The notching wheel 22 is attached to the arbor 88 by a support sleeve which is slidably positioned over the arbor 88 and which is held on the support sleeve by a nut 92 which is fastened upon the threads of the support sleeve 99. A spring 100 is positioned on a minor portion 87 of the arbor 88 so as to abut a major portion 8? of the arbor 88 and to resiliently press the slidable support sleeve 90 against the adjustable bearing 94.

As mentioned above the yoke 32 is adjustably secured by the clamp 30 so that the notching wheel 22 may be positioned at various angles (or pitches) with respect to the side rod 18 (as shown in FIG. 2). As will be explained later in detail, it has been found desirable to put various slots or notches into the side rods 18 at angles positive and negative with respect to a normal to the side rod 18. As a result of placing the notching wheel 22 at an angle with respect to the side rod 18, it has been found that the trailing edge of the groove in the side rod 18 has tended to become plowed. This irregularity in the slot is due to the fact that the side rod 18 is being constantly pulled linearly as it is being rotated beneath the notching wheel 22. Therefore, in order to insure an accurate and well formed notch, the spring 100 has been placed so as to resiliently bias the notching wheel 22 so that in effect the notching wheel 22 may ride with the side rod 18 as it is being pulled through the lathe. The particular embodiment shown in FIG. 3 depicts the spring 100 placed to the left of the notching wheel 22; this particular embodiment would enable a notching wheel 22 set at a positive angle with respect to the normal to rod 18 (i.e., a notching wheel rotated slightly counterclockwise as viewed in FIG. 2) to make a straight notch through the side rod 18. However, if the notching wheel 22 was mounted so as to form a negative angle with respect to the side rod 18 (as shown in FIG. 2) the spring would be mounted to the right of the notching wheel 22 so as to abut against the base portion of the support sleeve 90 which would have been inverted upon arbor 88. By so readjusting the biasing of spring 100, the notching wheel 22 would ride with the side rod 18 to make a clean cut.

FIGURE 4 shows a specific embodiment of an electron tube device in which the aligned concentric grid electrodes of this invention may be placed. The electron tube device comprises an evacuated envelope 40 which is hermetically sealed by a method Well known in the art to a base 53. A cathode 52 is centrally orientated within the electron tube device with an inner grid 44 and an outer grid 46 coaXially mounted thereabout. An anode or target 42 is mounted about the outer grid 46. The cathode 52, the anode 42 and the grids 44 and 46 are assembled into a unitary structure by being placed in suitable apertures within insulating spacers 48 and 50. The various electrodes of the electron tube device are connected to terminals 60 which extend from the base 58 by leads 62.

In FIGURE 5, there is shown a concentric grid structure which typically represents the attempts of the prior art to align the active portions of the coaxial grid electrodes. In particular, the grid electrode assembly comprises two coaxial grids 44a and 45:: mounted respectively on the inner side rods 54a and the outer side rods 56a. The inner grid 44a and the outer grid 46a have been so adjusted that the centers of their active portions will cross. At best, the inner grid 44a and the outer grid 46:: may be only aligned to coincide at the point of intersection of the two grids. "In the usual process of assembling electrode structures the cathode, the grid electrodes and the anodes are assembled into unitary structure formed of these elements and insulating spacers. These electrode elements are first loosely assembled upon the insulating spacers. In the case of the electron tube device with coaxial grids, it is the usual practice to first fixedly secure the side rods of the inner grid 44a to the insulating spacers by such means that are well known in the art such as welding or crimping. The next step would be to visually align from one side the outer electrode grid 46:: so that the active portions of the grid wires of the outer grid electrode 46a would intercept the active portions of the grid wires of the inner grid electrode 44a at its center point. This adjustment is usually accomplished by hand; the outer grid rods 56:: are adjusted upwardly and downwardly until the grid electrodes are aligned. In practice, it has been found necessary to then adjust the outer grid electrode 46a as viewed from the other side of the assembly. Due to the fact that the inner and outer grid electrodes are inherently askewed with respect to each other it has been found nearly impossible to align each turn of the grid electrodes. In aligning the lateral portions, the assembler attempts to have the active portions coincide at their center. This is accomplished by attempting to judge the magnitude of the angles which the grid wires make with each other (see FIG. and to make these angles approximately equal. Due to the fact that it is impossible to wind the grid wires with perfect regularity upon the side rod and that the turns of the grid will be slightly deformed by manipulating the side rods upon which the grid wire is secured, it is necessary to align the outer grid electrode from the other side of the assembly. Further, even after the grid electrodes have been so aligned, this alignment may be destroyed when the grid electrodes are heated during additional processing of the electron device and the stresses placed upon side rods during alignment will cause them to return to their preadjusted positions.

In FIGURE 6, there is shown a grid electrode assembly which comprises one embodiment of this invention. The grid electrode assembly includes an inner grid electrode 44 and an outer grid electrode 46 wound respectively about the inner side rods 54 and the outer side rods 56. In FIGURE 9, there is shown a plan view of the grid electrodes 44 and 46; the grid electrodes 44 and 46 are wound into a rectangular shape with connecting portions 45 and 47 in immediate association with the side rods 54 and 56. Active portions 43 and 49 extend along the lateral or major diameter of the grid electrodes interconnecting the connecting portions 45 and 47. The rectangular shape of the grid electrodes 44 and 46 is a result of the configuration of the mandrel 20 upon which the grid electrodes are wound, and the sizing mandrel upon which the grids are shaped. It is noted that the exact configuration of the electrodes 44 and 46 may not form precise rectangles; rather, the points of intersection between connection portions 45 and 47 and active portions 43 and 49 may be less defined than shown in FIGURE 9. As shown in FIGURE 6, the inner and outer grid electrodes coincide exactly with each other over the active portion 43 of the inner grid electrode 44. This alignment (as will be explained) is made possible by placing a pluralty of correction notches or slots in each of the side rods 54 and 56.

Referring now to FIGURES 7 and 8, there is shown the inner and outer side rods 54 and 56. In each of the side side rods there has been cut a correction slot or 72) to achieve the variations of the pitch of the connection portions 45 and 47 which are secured within these slots and to thereby prealign the active portions 43 and 49 of the coaxial grid electrodes 44 and 46. In order to understand the nature of the improvement made by this invent-ion, the method of winding the typical electrode grid shown in FIG. 5 must be explained. Usually, the grid wires are wound about the side rods 54a or 56a in a linear fashion; i.e., if the locus of the grid configuration was viewed in a single plane, it would appear as a straight line. The angle or pitch of the line or locus made by the grid wire is usually determined by the number of turns per unit of measurement of which the grid electrode is wound. The grid rods are notched as explained above by a notching wheel 22 and the grid wire 34 is secured within the notch. The angle or pitch of the notch is made equal to the pitch with which the grid wire is wound. In FIGURES 7 and 8, the angle designated by a1, depicts the pitch at which the grid wire of the inner grid electrode 44a of FIGURE 5 was wound and the angle at which the notch was cut into side rod 54a; and the angle designated by 023 illustrates the pitch at which the outer grid electrode 46a has been wound and the angle. at which the notch has been placed into the side rod 56a.

In the present invention, the pitch of the grid wire does not remain constant and if the locus of the grid electrode was viewed in a single plane it would resemble a zig-zag line. This variation in the pitch of the grid wire is achieved by placing the correction slots 70 and 72 in their respective side rods 54 and 56 at an angle that differs from the linear pitch determined by the turns per unit of measurement. In effect as the wire is being wound upon the grid lathe (see FIG. 1), it is placed into the correction slots 70 and 72 which action forces the grid wire to assume a slightly diiferent pitch or angle than the linear pitch. To restate the result, the connection portions 45 and 47 of the grid wire are realigned as they are forced into slots 70 and 72 so that the remaining portions of the grid wire including the active portions 43 and 49 are wound at a difiierent pitch.

The resultant product of this winding operation is to achieve an alignment between the active portions of the inner and outer grid electrodes 44 and 46 while winding the electrodes at the same turns per unit of measurement. In FIGURES 7 and 8, the correction slots 70 and 72 have been cut into their respective grid rods 54 and 56 at angles indicated as 0:2 and 0:4 with respect to a normal to the side rods. By comparing FIGURES 5 and 6, the effect of the correction slots may be seen upon the active portions of the grid electrodes 44 and 46. In FIGURE 5, the grid electrode 44a and 46a tend to diverge as they pass from their point of intersection. In FIGURE 6, the connection portions of the outer grid electrode 46 have been rotated about the side rods 56 to impart a slightly dificrent pitch to the active portions 43 and 49 from that shown in FIG. 5. Correspondingly, the connection portions of the grid electrodes 44 have been rotated in an opposite sense from that of grid electrode 46 so that the grid electrodes will align with the active portions 43 and 49 of the grid electrodes 46 and 44 at same pitch or angle.

As a practical matter, it has been found necessary to incorporate a degree of correction in both of the connection portions of the grid wires 46 and 44. In most vacuum tube devices, the ratio of the major diameter of the inner grid electrode to the major diameter of the outer grid electrode is such that it would be impractical to place all of the compensation in a single correction slot. As shown in FIGURES 7 and 8, correction slots 76 and 72 have been cut into the side rods 54 and 56 respectively at angles a2 and 14 with respect to a normal to the side rods. It has been discovered that the amount of angular correction needed is proportional to the ratio of the major diameters of the inner and outer grid electrodes. Further, the specifications of many electron devices with concentric grid electrodes require a ratio of the major diameters of the electrodes of approximately 1.5. Therefore, a set of angles (a2 and 114) which have been calculated for one grid electrode assembly would be suitable for another electrode assembly even though having significantly larger or smaller major diameter dimensions as long as the ratio of the major diameters remains approximately 1.5.

In a specific embodiment, as shown in FIGURES 6, 7, 8 and 9, the inner grid electrode 44- has a major diameter of .290 inch and a minor diameter of .080 inch; the outer grid electrode 46 has a major diameter of .460 inch and a minor diameter of .120 inch. In FIG. 6, the grid electrodes 44 and 46 have been wound in a right-hand manner about their respective side rods. As shown in FIGURES 7 and 8, the angle 012 has been aligned positively with respect to the uncorrected angle a1; further, the angle :14 has been set negatively with respect to the uncorrected angle (13. It is noted that the grid electrodes 44 and 46 could have been wound in a left-hand fashion; in such an arrangement, the corresponding correction angles a2 and a4 would be respectively aligned positively and negatively with respect to their uncorrected angles as viewed in such a left handed system.

It has been calculated by graphical and geometrical analysis that to provide an approximately equal correction in each of the grid electrodes 44 and 46, that the correction angles (12 and 014 would be 4.5 and 1.5 respectively. It is noted that any combination of angles whose sum is 6 could be used subject to the limitations of the materials and machines involved. The specific angles of 4.5 and 1.5 have been used in the specific embodiment of the grid electrodes 44 and 46 described above and have proved in actual experience to provide aligned grid structures. However, as noted above, though these angles have been computed for a specific embodiment, that these approximate angles could be used for the electrode grid assemblies of many electron devices.

As a result of preadjusting the lateral grid wires of the inner and outer electrode grids 44 and 46, the process of assembling the concentric grid electrodes between the insulating plates 48 and 50 has been materially simplified. The manufacturing of grid electrode assemblies comprises the operations of winding each of the grid electrodes upon a grid lathe with a predetermined correction slot placed in each of the side rods so as to prealign each of the grid wires. The next operation would be to cut the long length of helically wound grid rod wires into individual electrode grids and to further shape the grid electrode on a sizing mandrel. Then the inner electrode grid 44 and the outer electrode grid 46 as well as the cathode 52 and the anode '42 would be assembled between the insulating spacers 48 :and 50. In this assembling process, the inner grid electrode 44 would be first secured in its respective apertures of the insulating plates 50 and 48 by any of the means well known in the art such as welding or crimping. Next a technician will align the outer grid electrode 46 so that the grid wires will overshadow or align with each other. This step is typically performed by viewing the grid electrodes from a side view and manipulating the outer side rods 56 until the center points of the active portions of the grid wires have fallen into place. Because the active portions of the grid electrodes have been prealigned to form a common angle with respect to their respective side rods, the alignment of the outer grid electrode 46 has been materially simplified. Instead of attempting to align only the center portions of the respective grid electrodes (see FIG. alignment is accomplished by sighting along the entire length of the grid electrode and by adjusting the side rods .56 to bring the adjacent active portions into alignment. Due to the prealigned relation of the active portions, the initial adjustment of the outer side rods 56 is simplified and the helical configuration of grid wires is not thereby deformed. Further, it is not necessary to align the lateral grid wires from the other side of the electrode assembly. In the electrode assembly of this invention when the grid wires are correctly aligned on one side of the assembly, they will automatically be aligned on the other. As a result, a material saving in labor has been achieved by eliminating a second alignment of the grid assembly which would necessarily involve a prolonged and tedious sighting and manipulating operation.

It will, therefore, be apparent that there has been disclosed an electronic tube device which is capable of a more elficient performance and which may be assembled with less expenditure of labor. Actual experience has shown that precise correction grooves may be placed in side rods by a grid lathe. The grid electrodes so wound are capable of being easily assembled so that they may be aligned with an accuracy and case which was unknown in the prior art.

While there has been shown and described what are presently considered to be the preferred embodiments of this invention, modifications thereto will readily occur to those skilled in the art. It is not desired, therefore, that the invention be limited to the specific arrangements shown and described and it is intended to cover in the appended claims all such modifications as thought within the true spirit and scope of the invention.

We claim as our invention:

1. The method of manufacturing and assembling a control grid assembly having at least an inner and outer grid electrode, the method comprising the steps of winding the inner grid electrode upon a lathe by simultaneously placing a groove in the side rods at a first angle measured with respect to a normal to the side rods, and placing the grid wire into said groove, winding the outer grid electrode upon a lathe by simultaneously placing a groove in the side rods at a second angle measured with respect to a normal to the side rods, and placing the grid wire into the groove, said first and second angles totaling approximately 6", cutting said grids to given lengths, assembling said inner and outer grid electrodes into unitary arrangement, and the step of aligning adjacent grid electrodes by a single adjustment to the outer grid electrode.

2. The method of manufacturing and assembling a control grid assembly having at least an inner and outer grid electrode and an insulating support means, the method comprising the steps of winding the inner grid electrode upon a lathe by simultaneously placing a groove in the side rods of said inner grid electrode at an angle of approximately four and a half degrees positive with respect to a normal to said side rods and placing a grid wire into said groove, winding the outer grid electrode upon a lathe by simultaneously placing a groove in the side rods of said outer grid electrode at an angle of approximately one and a half degrees negative with respect to a normal to said side rods and placing a grid wire into said groove, cutting said grids to given lengths, assembling said inner and outer grid electrodes on said supporting means, and aligning the adjacent portions of the grid electrodes by a single adjustment to the outer grid electrode.

3. The method of manufacturing and assembling a control grid assembly having at least an inner and outer grid electrode, the method comprising the steps of winding the inner grid electrode upon a lathe by placing a groove by means of a notching wheel of said lathe in the side rods of said inner grid electrode at a first angle measured with respect to a normal to the side rods of said inner grid electrode and placing a grid wire into said groove, readjusting the notching wheel of said lathe with respect to side rods, winding the outer grid electrode upon said lathe by placing a groove by means of the notching of said lathe in the side rods of said outer grid electrode at a second angle measured with respect to a normal to the side rods of said outer grid electrode and placing a grid Wire into said groove, said first and second angles totaling substantially 6, cutting said grids to given lengths, assembly said inner and outer grid electrodes into a unitary structure, and aligning the adjacent portions of the grid electrodes by a single adjustment to the outer grid electrode.

4. A method of manufacturing an electrode assembly including at l ast first and second electrodes, said first and second electrodes each comprising at least one support rod and a coil, said method of manufacturing comprising the steps of: forming said coil of said first electrode and disposing said coil of said first electrode upon said rod of said first electrode at a first angle measured with respect to a normal to said rod of said first electrode; and forming said coil of said second electrode and disposing said coil of said second electrode upon said rod of said second electrode at a second angle measured with respect to a normal to said side rod, so that the sum of said first and second angles substantially equals 6".

5. The method of manufacturing as claimed in claim 4, wherein said first angle is determined to be approximately 1.5 and said second angle is determined to be approximately 4.5

6. The method or" manufacturing an electrode assembly including at least first and second electrodes, said first and second electrodes each comprising at least one support rod and a coil, said method of manufacturing comprising the steps of: Winding said coil of said first electrode with a predetermined turns per unit of measurement and disposing said coil of said first electrode upon said rod of said first electrode at a first angle positive With respect to the mean slope of said coil of said first electrode; and Winding said coil of said second electrode with said predetermined turns per unit of measurement and disposing said coil of said second electrode upon said rod of said second electrode at a second angle negative with respect to the mean slope of said coil of said second electrode.

7. A method of manufacturing as claimed in claim 6, wherein said coil of said first electrode is disposed so that said first angle is positive with respect to a normal to said rod of said first electrode and said coil of said second electrode is disposed so that said second angle is negative With respect to a normal to said side rod of said second electrode.

8. A method of manufacturing as claimed in claim 7,

wherein said first angle equals substantially 4.5 and said second angle equals substantially 1.5.

The Canadian Patent Ofiice Record, vol. 72, July-Septernber 1944, Abstract of Canadian Pat. No. 422,257, to Shade, Aug. 22, 1944, pp. 22362237.

CHARLES VJ. LANHAM, Primary Examiner.

L. A. LARSON, Assistant Examiner. 

1. THE METHOD OF MANUFACTURING AND ASSEMBLING A CONTROL GRID ASSEMBLY HAVING AT LEAST AN INNER AND OUTER GRID ELECTRODE, THE METHOD COMPRISING THE STEPS OF WINDING THE INNER GRID ELECTRODE UPON A LATHE BY SIMULTANEOUSLY PLACING A GROOVE IN THE SIDE RODS AT A FIRST ANGLE MEASURED WITH RESPECT TO A NORMAL TO THE SIDE RODS, AND PLACING THE GRID WIRE INTO SAID GROOVE, WINDING THE OUTER GRID ELECTRODE UPON A LATHE BY SIMULTANEOUSLY PLACING A GROOVE IN THE SIDE RODS AT A SECOND ANGLE MEASURED WITH RESPECT TO A NORMAL TO THE SIDE RODS, AND PLACING THE GRID WIRE INTO THE GROOVE, SAID FIRST AND SECOND ANGLES TOTALING APPROXIMATELY 6*0, CUTTING SAID GRIDS TO GIVEN LENGTHS, ASSEMBLING SAID INNER AND OUTER GRID ELECTRODES INTO UNITARY ARRANGEMENT, AND THE STEP OF ALIGNING ADJACENT GRID ELECTRODES BY A SINGLE ADJUSTMENT TO THE OUTER GRID ELECTRODE. 